1. Field of the Invention
The present invention relates to a mobile machine for cleaning a bed supporting a track consisting of two rails fastened to ties, particularly a ballast bed wherein the track ties are embedded, which comprises a machine frame and undercarriages supporting the machine frame on the track rails for mobility in an operating direction. A suction arrangement on the machine frame comprises a suction head means having an inlet port means, suction conduit means, a ventilator connected to the suction head means by the suction conduit means for producing suction at the inlet port, and a receptacle incorporating a filter connected to the suction conduit means, and a compressed air generating arrangement associated with the suction arrangement comprises compressed air discharging nozzle means, compressed air conduit means, and compressed air generator means connected to the nozzle means by the compressed air conduit means, the suction and compressed air generating arrangements forming a substantially closed pressure-suction system.
2. Description of the Prior Art
An advertisement on page 462 of the periodical "Der Stadtverkehr", 11/12, 1980, covers such a mobile machine for cleaning the surface of a track with a pressure-suction system. The advertised machine comprises two vehicles coupled together for respectively cleaning one half of the track. The pressure-suction system is described in some detail in an article on page 3, No. 8, 1980, of the same periodical, in connection with the suction system of similar track cleaning vehicles. In accordance with the sketch shown in page 3, the suction arrangement comprises a suction head, a suction conduit having an inlet port, a ventilator having a radial blower connected to the suction head by the suction conduit for producing suction in the inlet port, and a receptacle incorporating a filter connected to the suction conduit. The suction arrangement is termed a pressure-suction nozzle, and a bell-shaped pressure nozzle is associated with the suction head, a pressure conduit connecting the radial blower to the pressure nozzle. The suction head is arranged within the bell-shaped pressure nozzle and the air flowing under pressure through the pressure conduit from the radial blower to the pressure nozzle is sucked with dirt into the inlet port and thence through the suction conduit into the receptacle. Such a machine with two coupled vehicles is relatively expensive. Furthermore, the pressure nozzle surrounding the suction head requires a considerable suction force to prevent the surface ballast from being blown away or a dust cloud from rising through openings defined between the edge of the pressure nozzle and the surface of the ballast bed.
German Pat. No. 2,217,975, published Dec. 20, 1979, disclosed a mobile suction machine for cleaning the surface of a ballast bed, which comprises a machine frame supported by undercarriages for mobility on the track and carrying a receptacle, a filter and a ventilator. A suction arrangement is mounted between the two undercarriages on a carriage linked to the machine frame by rods, the suction arrangement being constituted by a suction head extending over the entire track width. Except at the tie ends, the inlet port of the suction head is delimited by vertically adjustable edge stripping comprised of several transversely adjacent and independently vertically adjustable strips forming pairs of air guide elements at both sides of the inlet port. The suction arrangement comprises suction conduits connected to a receptacle. The independently operable air guide elements are particularly useful for operation of the machine in track switches. The construction is quite elaborate and the lower portions of the air guide strips are subject to considerable wear. Furthermore, the arrangement is not capable of removing encrusted dirt from the surface of the ballast bed.
An article on pages 14-21, No. 4, 1987, of the periodical "Der Nahverkehr" discloses different self-propelled vacuum cleaner trains most of which operate on the pressure-suction principle. These machines are used for surface cleaning of short-distance tracks, such as subways or commuter railroads. Because such tracks are dirtied by such debris as cigarette butts, paper and the like, as well as by brake sand, dust and metallic abrasions from the rails, this problem of track surface cleaning has received added attention not only to improve the appearance of the tracks but also to maintain the elasticity of the ballast bed by reducing its encrustation by dirt. In these cleaning trains, the dust-containing air is cleaned by dry or wet filters. However, these rather complicated vacuum cleaner trains still fail to produce efficient cleaning and do not remove encrusted dirt strongly adhering to the ballast or dirt lodged below the surface between the ballast rocks.
Austrian Pat. No. 384,446, published Apr. 15, 1987, discloses a mobile machine for sucking the entire ballast out of a ballast bed. The removed ballast is cleaned on a screen arranged on the machine and the cleaned ballast is redistributed. The suction arrangement is vertically adjustable mounted on the machine frame and is comprised of three suction nozzles each having an inlet port and its own flexible suction conduit connected to the screen and a compressor. Ballast clearing tools rotatable in the track plane for loosening the ballast are associated with the suction nozzles. This machine has not yet been commercially used but does not appear to be adapted for cleaning the surface of a ballast bed.
Another machine designed for this purpose has been disclosed in German utility model No. 8,236,650 whose grant was published on June 30, 1983. This machine is equipped with a simple suction arrangement comprising a transversely and longitudinally displaceable suction head and a suction pipe connecting the suction head to a screening arrangement. Elastic, vertically adjustable edge strips are connected to the inlet port of the suction head to close off the inlet port, except for a receiving inlet oriented in the operating direction. The suction head is a nozzle of relatively small, round or rectangular cross section to enable the heavy ballast to be efficiently sucked in for subsequent cleaning. This machine cannot be used for cleaning the surface of a ballast bed.
Finally, German Pat. No. 1,244,221, published July 13, 1967, discloses a device for cleaning switches and rails, which may be mounted on a carriage. A vertically adjustable wagon is mounted between the front and rear wheels of the carriage and is equipped with a nozzle box associated with each rail. A suction, compressed air, pressurized water and lubrication nozzle are mounted in each box. It is not possible to clean the surface of a ballast bed with this machine.